1. Description of the Related Art
At present, some high frame rate televisions (over 120 Hz) or televisions with a tri-gate structure (or a tri-gate driving circuit) usually have the issue of insufficient charging, since the tri-gate scan frequency is too high, and the time of turning on a thin film transistor (TFT) is reduced. In general, pre-charging is a common measure taken to overcome the insufficient charge issue. In other words, the voltage of the Nth row is charged to the voltage of the (N+1)th row, and then a correct voltage is charged to the (N+1)th row. To reduce the capacitive coupling effect produced when turning off the switch of the thin film transistor (TFT), the falling edge of the gate driving voltage VGH signal of the TFT is cut at an angle. However, the angle cutting process will reduce the scan potential in the waveform of the voltage of the scan line when the pixels are pre-charged, and thus the electrical conduction of TFT is too low in the charging process, so as to affect the pixel charging effect and reduce the pre-charging effect.
2. Summary of the Invention
Therefore, it is a primary objective of the present invention to overcome the drawbacks of the prior art by providing a pixel charging method and circuit capable of improving the pixel charging effect.
To achieve the aforementioned and other objectives, the present invention provides a pixel charging method comprising the steps of: outputting a first driving signal to turn on an active switch of the Nth row scan line to pre-charge and charge an Nth row of pixels, wherein the first driving signal has no angle cutting in a predetermined first time period, and the predetermined first time period includes a period of time before and after the pre-charge of the Nth row of pixels is completed, and the first driving signal has an angle cutting in a predetermined second time period, and the predetermined second time period includes a period of time before the charge of the Nth row of pixels is completed, and N is a natural number; and outputting a second driving signal to turn on a switch of the (N+1)th row scan line to pre-charge and charge the (N+1)th row of pixels, wherein the second driving signal has no angle cutting in a predetermined third time period, and the predetermined third time period includes a period of time before and after the pre-charge of the (N+1)th row of pixels is completed, and the second driving signal has an angle cutting in a predetermined fourth time period, and the predetermined fourth time period includes a period of time before the charge of the (N+1)th row of pixels is completed, and the difference between the time point of completing the charge of the Nth row of pixels and the time point of outputting the second driving signal is positive and equal to or smaller than the pre-charging time of the (N+1)th row of pixels.
To achieve the aforementioned and other objectives, the present invention further provides a pixel charging circuit comprising: a scan driving circuit, for outputting a first driving signal to turn on an active switch of the Nth row scan line, and outputting a second driving signal to turn on a switch of the (N+1)th row scan line; a data driving circuit, for pre-charging and charging the Nth row of pixels when the first driving signal is outputted, and pre-charging and charging the (N+1)th row of pixels when the second driving signal is outputted; wherein the first driving signal has no angle cutting in a predetermined first time period, and the predetermined first time period includes a period of time before and after the pre-charge of the Nth row of pixels is completed, and the first driving signal has an angle cutting in a predetermined second time period, and the predetermined second time period includes a period of time before the charge of the Nth row of pixels is completed, and N is a natural number; the second driving signal has no angle cutting in a predetermined third time period, and the predetermined third time period includes a period of time before and after the pre-charge of the (N+1)th row of pixels is completed, and the second driving signal has an angle cutting in a predetermined fourth time period, and the predetermined fourth time period includes a period of time before the charge of the (N+1)th row of pixels is completed, and the difference between the time point of completing the charge of the Nth row of pixels and the time point of outputting the second driving signal is positive and equal to or smaller than the pre-charging time of the (N+1)th row of pixels.
To achieve the aforementioned and other objectives, the present invention further provides an LCD panel including the pixel charging circuit, and the pixel charging circuit comprises: a scan driving circuit, for outputting a first driving signal to turn on an active switch of the Nth row scan line, and outputting a second driving signal to turn on a switch of the (N+1)th row scan line; a data driving circuit, for pre-charging and charging the Nth row of pixels when the first driving signal is outputted, and pre-charging and charging the (N+1)th row of pixels when the second driving signal is outputted; wherein the first driving signal has no angle cutting in a predetermined first time period, and the predetermined first time period includes a period of time before and after the pre-charge of the Nth row of pixels is completed, and the first driving signal has an angle cutting in the predetermined second time period, and the predetermined second time period includes a period of time before the charge of the Nth row of pixels is completed, and N is a natural number; the second driving signal has no angle cutting in a predetermined third time period, and the predetermined third time period includes a period of time before and after the pre-charge of the (N+1)th row of pixels is completed, and the second driving signal has an angle of cutting in a predetermined fourth time period, and the predetermined fourth time period includes a period of time before the charge of the (N+1)th row of pixels is completed, and the difference between the time point of completing the charge of the Nth row of pixels and the time point of outputting the second driving signal is positive and equal to or smaller than the pre-charging time of the (N+1)th row of pixels.
To achieve the aforementioned and other objectives, the present invention further provides an LCD device including the LCD panel, and the LCD panel includes the pixel charging circuit, and the pixel charging circuit comprises: a scan driving circuit, for outputting a first driving signal to turn on an active switch of the Nth row scan line, and outputting a second driving signal to turn on a switch of the (N+1)th row scan line; a data driving circuit, for pre-charging and charging the Nth row of pixels when the first driving signal is outputted, and pre-charging and charging the (N+1)th row of pixels when the second driving signal is outputted; wherein the first driving signal has no angle cutting in a predetermined first time period, and the predetermined first time period includes a period of time before and after the pre-charge of the Nth row of pixels is completed, and the first driving signal has an angle cutting in a predetermined second time period, and the predetermined second time period includes a period of time before and after the charge of the Nth row of pixels is completed, and N is a natural number; the second driving signal has no angle cutting in a predetermined third time period, and the predetermined third time period includes a period of time before and after the pre-charge of the (N+1)th row of pixels is completed, and the second driving signal has an angle cutting in a predetermined fourth time period, and the predetermined fourth time period includes a period of time before the (N+1)th row of pixels is completed, and the difference between the time point of completing the charge of the Nth row of pixels and the time point of outputting the second driving signal is positive and equal to or smaller than the pre-charging time of the (N+1)th row of pixels.
In the present invention, two driving signals are used for driving two adjacent scan lines to pre-charge and charge the row of pixels. When the pixel of a row is charged, the pixel of the next row is pre-charged. After the pre-charge of the pixel is completed, the charging of the pixel starts immediately, and there is no angle cutting in a certain period before the pre-charge is completed, so that after the pre-charge of the pixel ends and the charging of the pixel starts, the active switch is turned on completely without affecting the actual charging process, in order to improve the effect of charging the pixel.